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Dive into the research topics where Y. Maehara is active.

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Featured researches published by Y. Maehara.


American Journal of Transplantation | 2006

Feasibility of left lobe living donor liver transplantation between adults: An 8-year, single-center experience of 107 cases

Y. Soejima; Akinobu Taketomi; T. Yoshizumi; Hideaki Uchiyama; Noboru Harada; Hideki Ijichi; Yusuke Yonemura; Mitsuo Shimada; Y. Maehara

Operative mortality for a right lobe (RL) donor in adult living donor liver transplantation (LDLT) is estimated to be as high as 0.5–1%. To minimize the risk to the donor, left lobe (LL)‐LDLT might be an ideal option in adult LDLT. The aim of the study was to assess the feasibility of LL‐LDLT between adults based on a single‐center experience of 107 LL‐LDLTs performed over 8 years. The mean graft weight of LL grafts was 452 g, which amounted to 40.5% of the estimated standard liver volume of the recipients. The overall 1‐, 3‐ and 5‐year patient survival rates in LL‐LDLT were 81.4, 76.9 and 74.7%, respectively, which were comparable to those of RL‐LDLT. Twenty‐six grafts (24.3%) were lost for various reasons with three losses directly attributable to small‐for‐size graft syndrome. Post‐operative liver function and hospital stay in LL donors were significantly better and shorter than that in RL donors, while the incidence of donor morbidity was comparable between LL and RL donors. In conclusion, LL‐LDLT was found to be a feasible option in adult‐to‐adult LDLT. Further utilization of LL grafts should be undertaken to keep the chance of donor morbidity and mortality minimal.


British Journal of Surgery | 2005

Effective follow-up for recurrence or a second primary cancer in patients with early gastric cancer

Yasuharu Ikeda; Motonori Saku; Fumiaki Kishihara; Y. Maehara

Patients with early gastric cancer have an excellent prognosis with low rates of recurrence, but may have an increased risk of developing a second primary cancer. Because the number of early gastric cancers has increased, clarification of both recurrences and second primary cancers is important for the development of effective postoperative follow‐up programmes.


British Journal of Surgery | 2004

The hydroxyl radical scavenger MCI-186 protects the liver from experimental cold ischaemia-reperfusion injury

Mizuki Ninomiya; Mitsuo Shimada; Noboru Harada; Y. Soejima; Taketoshi Suehiro; Y. Maehara

Oxidative stress contributes to hepatic ischaemia–reperfusion (IR) injury in a biphasic pattern. In addition to direct cytotoxic effects, oxidative stress also initiates the signal transduction processes that promote second‐phase liver injury. The present study investigated the effects of the hydroxyl radical scavenger MCI‐186 on the biphasic process of hepatic cold IR injury.


American Journal of Transplantation | 2014

Revisiting the Safety of Living Liver Donors by Reassessing 441 Donor Hepatectomies: Is a Larger Hepatectomy Complication‐Prone?

Hideaki Uchiyama; Ken Shirabe; Hidekazu Nakagawara; Toru Ikegami; Takeo Toshima; Y. Soejima; T. Yoshizumi; Yamashita Y; Norifumi Harimoto; Ikeda T; Y. Maehara

Donor safety is of paramount importance in performing living donor liver transplantation (LDLT). We retrospectively reviewed donor medical records to confirm whether larger donor hepatectomy is absolutely complication‐prone. A total of 441 living donor hepatectomies were performed between October 1996 and July 2012 in our institute, which were divided into three eras (Era I, October 1996 to March 2004; Era II, April 2004 to March 2008; Era III, April 2008 to July 2012) and the incidences of postoperative complications were compared among the three types of hepatectomy—right hepatectomy (RH), left hepatectomy (LH) and left lateral segmentectomy (LLS). Although severe complications (Claviens grade 3 or more) frequently occurred in RH in Eras I and II (15.4% and 10.7%, respectively), the incidence in Era III decreased to the comparable level observed in LH and LLS (5.4% in RH, 2.3% in LH and 5.3% in LLS). The incidence of postoperative complications did not relate to the type of hepatectomy selected in the latest era. Since most complications after hepatectomy were considered preventable, step‐by‐step meticulous surgical procedures are a prerequisite for further assuring donor safety irrespective of the type of hepatectomy selected.


Transplantation Proceedings | 2008

Estimation of standard liver volume for Japanese adults.

Tomoharu Yoshizumi; Akinobu Taketomi; Hiroto Kayashima; Yusuke Yonemura; Noboru Harada; Hideki Ijichi; Y. Soejima; Takashi Nishizaki; Y. Maehara

INTRODUCTION Accurate pretransplant estimation of the recipients standard liver volume (SLV) is important. The purpose of this study was to compare reported formulas for clinical estimation of liver volume among Japanese adults. METHODS We reviewed data on 70 healthy adults (46 men, 24 women, ages 20 to 65 years old) evaluated for living donor liver transplantation. Liver volume (LV) was measured using two- or three-dimensional computed tomography volumetry (CTV). The formulas of DeLand (LV = 1020 x body surface area [BSA] - 220), Urata (LV = 706.2 x BSA + 2.4), Noda (LV = 50.12 x BW(0.78)), Heinemann (LV = 1072.8 x BSA - 345.7), Vauthey (LV = 18.51 x BW + 191.8) and Yoshizumi (LV = 772 x BSA) were applied to estimate LV. We calculated the differences for individual donors betwen CTV and LV estimated by each formula. RESULTS Mean LVs as estimated by the formulae of DeLand and Heinemann et al were significantly greater (P < .01) than the mean CTV, while LV estimated by the formula of Urata was significantly less (P < .05) than the CTV. The formulas of DeLand and Heinemann overestimated LV, while the formula of Urata underestimated it. The formulae of Noda et al and Yoshizumi et al tended to underestimate the LV when the CTV was greater than 1600 cm(3). When the Yoshizumi formula was applied, the number of donors with an acceptable difference (+/-15%) between CTV and estimated LV was 55 (78.6%). CONCLUSIONS The Yoshizumi formula was applicable, especially for patients with a BSA < 2.0, whereas the well-known Urata formula made LV underestimates.


Transplantation Proceedings | 2008

Donor Age in Living Donor Liver Transplantation

Toru Ikegami; Akinobu Taketomi; Ryuji Ohta; Y. Soejima; T. Yoshizumi; Mitsuo Shimada; Y. Maehara

BACKGROUND We sought to elucidate the influence of donor age in living donor liver transplantation (LDLT) using either left lobe (LL) or right lobe (RL) grafts. METHODS Recipients (n = 232) were categorized as: group O/LL (LL, donor age >50, n = 20); group Y/LL (LL, donor age < or =50, n = 140); Group O/RL (RL, donor age >50, n = 12); and group Y/RL (RL, donor age < or =50, n = 61). We compared post-LDLT graft functions. RESULTS Among LL LDLT, the incidence of small-for-size syndrome was significantly greater for group O/LL compared with group Y/LL (60.0% vs 16.3%, P < .01). However, the cumulative 5-year graft survivals were 73.8% in group O and 76.7% in group Y without substantial difference. In RL LDLT, the post-LDLT morbidity and mortality were similar for group O/RL and group Y/RL. CONCLUSION Partial liver grafts, even though LL grafts, from older donors can be used safely with caution in LDLT.


British Journal of Surgery | 2014

Effect of laparoscopic splenectomy on portal haemodynamics in patients with liver cirrhosis and portal hypertension.

H. Kawanaka; Tomohiko Akahoshi; Nao Kinjo; Tomohiro Iguchi; Mizuki Ninomiya; Yamashita Y; Toru Ikegami; T. Yoshizumi; Ken Shirabe; Y. Maehara

The effect of splenomegaly in patients with liver cirrhosis and portal hypertension is not fully understood. This study was designed to determine the effect of laparoscopic splenectomy on portal haemodynamics in these patients.


Transplant International | 2005

Blockage of the macrophage migration inhibitory factor expression by short interference RNA inhibited the rejection of an allogeneic tracheal graft

Seiichi Fukuyama; Ichiro Yoshino; Masafumi Yamaguchi; Atsushi Osoegawa; Toshifumi Kameyama; Tetsuzo Tagawa; Y. Maehara

We investigated the inhibitory effect of blocking the macrophage migration inhibitory factor (MIF) on the fibrous obstruction of a transplanted allograft in a murine model of obstructive bronchiolitis (OB). Tracheal grafts from C57BL/6 mice were transplanted into a subcutaneous pouch of BALB/c. Three days after transplantation, liposome including short interference (si) RNA for MIF was injected into the lumen of the grafts. The allografts were then harvested 7, 14 or 28 days after transplantation for an evaluation of the morphological changes. The MIF expression, which was ubiquitously recognized in the epithelium of allografts, decreased after the in vivo transfection of MIF siRNA. OB formation was therefore inhibited significantly more by the treatment with MIF siRNA than the allografts injected with empty liposome on the 14th day, however, no difference was observed between them on the 28th day. Treatment with MIF siRNA inhibits the destruction of tracheal allografts and OB formation in the early phase, and MIF was thus found to be one of the major cytokines involved in the rejection of the allogeneic trachea.


Scandinavian Journal of Surgery | 2013

Human Early Liver Regeneration after Hepatectomy in Patients with Hepatocellular Carcinoma: Special Reference to Age

Ken Shirabe; Takashi Motomura; Kazuki Takeishi; Kazutoyo Morita; Hiroto Kayashima; Akinobu Taketomi; Toru Ikegami; Y. Soejima; T. Yoshizumi; Y. Maehara

Background and Aims: This study was conducted to clarify the effects of age on human liver regeneration. Patients and Methods: Thirty major hepatectomies, equal to or more than two segmentectomies for hepatocellular carcinoma, were performed. Ages ranged from 37 to 85 years and five octogenarians were included. The early regenerative index was defined: (liver volume after 7 days after hepatectomy − estimated remnant liver volume before hepatectomy)/estimated remnant liver volume, using three-dimensional computed tomographic volumetry. Farnesoid X receptor and forkhead box m1 expression in the liver, which has been reported to age-related decrease of liver regeneration in animal model, were examined using real-time polymerase chain reaction. The patients were divided into two groups: low early regenerative index (n = 15), early regenerative index less than 55% and high early regenerative index (n = 15), early regenerative index equal to or more than 55%. Results: The mean early regenerative index was 57%. Age (R2 = 0.274, P = 0.003) and estimated blood loss (R2 = 0.134, P = 0.0466) were inversely correlated with the early regenerative index, and the expression of farnesoid X receptor and forkhead box m1 was not. The incidence of posthepatectomy liver failure in the low early regenerative index group was higher than that in the high early regenerative index group (P = 0.0421). Conclusions: Age and intraoperative blood loss are inversely correlated with early liver regeneration in humans. In elderly patients, massive blood loss should be avoided in view of liver regeneration.


Transplantation Proceedings | 2009

Rapid normalization of portopulmonary hypertension after living donor liver transplantation.

Keizo Sugimachi; Y. Soejima; Kazutoyo Morita; Shigeru Ueda; Takasuke Fukuhara; Shigeyuki Nagata; Toru Ikegami; Akinobu Taketomi; Y. Maehara

Portopulmonary hypertension (PPHTN) is a relatively rare complication of end-stage liver disease, and a serious problem in the context of liver transplantation. Herein we have reported a case of decompensated liver cirrhosis with PPHTN, which rapidly resolved after adult-to-adult living donor liver transplantation (LDLT). A 54-year-old man was referred to our hospital with end-stage liver cirrhosis owing to chronic hepatitis C. Preoperative mean pulmonary artery pressure (mPAP), as assessed by right heart catheterization, was 38 mm Hg. Continuous infusion of epoprostenol decreased the mPAP to 24 mm Hg over 44 days. He underwent LDLT using a right hepatic lobe graft donated by his son. The postoperative course was uneventful, epoprostenol was weaned by postoperative day (POD) 21, and the mPAP normalized to 21 mm Hg on POD 28. The patient was discharged on POD 31 without any vasodilators. Our case revealed that liver transplantation can rapidly resolve PPTHN.

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